Standard vector magnetometers detecting the strength and direction of the magnetic field are typically limited to sensing a single vector component of the sensed magnetic field. Tri-axial detection requires a configuration of three discrete single-axis sensors packaged discretely and aligned precisely along the orthogonal x, y, and z axes to accurately reconstruct the total magnetic field. See FIG. 1a. A three sensor chip configuration is more susceptible to environmental gradient effects (i.e. thermal, mechanical, and magnetic) due to the large distances between sensors than would be a single chip sensor such as that proposed herein and depicted by FIG. 1b. Die-to-die placement of the three discrete sensors also incur significant errors from the misalignment of the sensors along the orthogonal axes. During operation, the sensors' orientation can also drift due to vibration and thermal effects adding cross-axis coupling errors.
A dual-axis or tri-axial sensor like the proposed quartz magnetometer disclosed herein, can replace the previously described three-sensor configuration with a single die package where multi-vector field detection can be performed at the same location. The smaller volume coming from a single die ensures more consistent readouts as the environmental effects within a die are more uniform. Additionally, alignment accuracy is no longer dependent on die-to-die placement but on microfabrication processes which provides far better alignment precision (sub-micron) and accuracy. Alignment drifts from packaging is no longer a concern when the multi-axis detection schemes are implemented on a single device.
The prior art includes: “Development of Miniature Magnetometers” Dennis K. Wickenden, Thomas J. Kistenmacher, Robert Osiander, Scott A. Ecelberger, R. Ben Givens, and John C. Murphy, Johns Hopkins APL Technical Digest, Vol. 18, Num. 2 (1997) 271.
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